Shortly before 1.30pm on Tuesday, David Davis, the Brexit Secretary, opposed a House of Lords amendment in no uncertain terms.
Ministers saw off a move to give MPs the decisive say on what happens over Brexit if they do not agree with the deal negotiated by the United Kingdom government.
Two days of debate on the laws that will end Britain's European Union membership have crystallised long-running divisions within May's party about the best strategy for leaving the European Union, bringing to a head issues that will determine the relationship between the world's fifth-largest economy and its biggest trading bloc.
However, a potential rebellion by pro-Remain Tories over their demands for a "meaningful vote" on the final Brexit deal was only avoided after ministers agreed at the last moment to discuss a compromise.
A third development, which would allow MPs to direct the government on future talks if there is no resolution on the withdrawal agreement by 15 February, is also on the cards. This might convince some wavering "rebels" to back the government in order to save May and prevent Boris Johnson, the current foreign secretary and a leading so-called "Brexiteer", from seeking to replace her.
"The main reason for my taking this decision now is the Brexit process and the government's wish to limit parliament's role in contributing to the final outcome in a vote that takes place today", Lee, who voted to remain in the European Union during Britain's 2016 referendum, said on his website.
Earlier May suffered a setback when junior justice minister Phillip Lee, who has always been critical of Brexit strategy, resigned and said he would vote against the government. The victory was Pyrrhic, as the government's earlier climbdown all but ensures MPs will have an increased say on the terms of any deal. Philip Lee said a choice between "bad and worse" options was not giving MPs a meaningful vote. "We will now work with the government to get acceptable amendments tabled in the Lords to address this".More news: Trump takes credit for Sanford loss in SC primary
More news: What The North Korean Summit Means For Missile Defense In Hawaii
More news: GOP Moderates: Tentative Immigration Deal With Conservatives
The shock move came as the Prime Minister warned senior ministers in her Cabinet that defeat on a series of Lords amendments over the next two days would undermine the Government and make negotiations with Brussels harder.
"The question of what form parliamentary approval of the withdrawal bill takes is one of the most significant decisions this house will have to take", he said.
The Prime Minister appeared to have defused a potentially explosive row over the EU customs union on Monday night as Tory pro-Europe rebels Sir Oliver Letwin and Nicky Morgan and Brexiteers Jacob Rees-Mogg and Sir Bill Cash came together to table a separate compromise amendment backing "a customs arrangement" with the EU.
The rebels said on Tuesday they were told the promise made by the prime minister was "a matter of trust".
But government officials admitted that the concession does constrain their freedom in the Brexit talks. "There could be a confidence motion [in the prime minister] or an early general election".
"We cannot remain in the Customs Union and sign our own trade deals meaning that Britain could not make the most of the opportunities that Brexit presents".
Labour's Brexit policy chief, Keir Starmer, said May had been forced to avoid a "humiliating defeat" and "to enter negotiations with her backbenchers".